Oil supplying apparatus and method of controlling the same

ABSTRACT

An engine output shaft drives an engine driven pump. The engine driven pump pressurizes oil. An accumulator accumulates the pressurized oil. An electric motor drives a motor driven pump. When the engine rotates low speed, both the engine driven pump and the motor driven pump supply oil to an oil chamber of a belt type continuously variable transmission. If it is required to enlarge a capacity of the oil chamber quickly, the pressurized oil in the accumulator is supplied to the motor driven pump. The motor driven pump further pressurizes the pressurized oil in the accumulator and supplies it into the oil chamber. It is possible to supply a sufficient amount of oil to the continuously variable transmission. Additionally, since the system may be constructed by using a small type engine driven pump, it is possible to improve fuel efficiency.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based on Japanese Patent Application No. Hei11-160852 filed on Jun. 08, 1999, No. Hei 11-305270 filed on Oct. 27,1999 and No. 2000-129801 filed on Apr. 28, 2000 the contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a hybrid type oil supplyingapparatus and a method for controlling the apparatus having an internalcombustion engine (engine) driven pump and an electric motor drivenpump. For instance, the apparatus of the present invention can beapplied to a system for supplying oil for lubrication or an oil pressurecontrol.

[0004] 2. Description of Related Art

[0005] An engine driven pump is driven by an output shaft of the engine.An engine driven pump supplies an amount of oil depending on arevolution speed. For example, the amount of oil is little at a lowrevolution speed such as an idle operation. In a lubrication purpose, ifoil is not supplied sufficiently, lubricated portions might be sticked.On the other hand, in an oil pressure control purpose, if oil is notsupplied sufficiently, a responsive ability is lowered. For example, ina case that an oil pressure is used for varying a width-of a pulley of acontinuously variable transmission, it is required to supply oil quicklyinto a chamber for actuating the pulley. Here,if oil is not suppliedsufficiently, a time lag is generated at a changing operation.

[0006] On the other hand, at a high revolution speed, the amount of oilmight be excessive, the engine load increases wastefully, and fuelefficiency might be lowered.

SUMMARY OF THE INVENTION

[0007] It is an object of the present invention to provide an oil supplyapparatus to avoid an insufficiency of oil at low revolution speed.

[0008] It is another object of the present invention to provide an oilsupply apparatus to avoid an insufficiency of oil at low revolutionspeed and to improve fuel efficiency.

[0009] It is a further object of the present invention to provide an oilsupply apparatus requiring a small space to install it.

[0010] It is a still further object of the present invention to providean oil supply apparatus in which a required amount of oil can besupplied from a starting of an engine.

[0011] It is a yet further object of the present invention to provide acontrolling method of an oil supply apparatus in which a requiredtransmission ratio can be provided from a starting of the engine.

[0012] According to a first aspect of the present invention, the presentinvention includes a pump driven by an engine and a pump driven by anelectric motor. Therefore, the engine driven pump can be downsized so asto prevent an excessive oil supply. When an amount of oil supplied bythe engine driven pump is insufficient, a required amount of oil can besupplied by the motor driven pump. Further, it is possible to suppressthe engine load and to improve fuel efficiency by downsizing the enginedriven pump.

[0013] According to a second aspect of the present invention, thepresent invention includes an accumulator for accumulating oildischarged from the engine driven pump, and supplies oil in theaccumulator through the motor driven pump. Since the motor driven pumpis supplied oil accumulated at high pressure in the accumulator, themotor driven pump can introduce a sufficient amount of oil and therequired amount of oil can be supplied through the motor driven pumpeven the motor driven pump has a low suction performance. Therefore, themotor driven pump can be downsized.

[0014] According to a third aspect of the present invention, in a casethat a quick change of the transmission ratio is required, theaccumulator supplies the accumulated oil through the motor driven pump.

[0015] According to a fourth aspect of the present invention, the motordriven pump is driven when a controller stops the engine. Therefore, theengine can be restarted when oil is supplied to the engine. Forinstance, it is possible to suppress a shock generated in thetransmission because the engine can be restarted when the pressurizedoil is supplied to an oil pressure control device of the automatictransmission. For instance, it is effective to drive the motor drivenpump when the engine temporarily stopped by an operation of an idle-stopcontrol. Further, in a belt type continuously variable transmission, themotor driven pump is controlled to maintain a pressure that can hold thebelt. Here, a delay time from a stopping of the engine to a starting ofthe motor driven pump is preferably set according to a characteristicfor maintaining the oil pressure. The motor driven pump may becontrolled according to the oil pressure. For instance, the pump isstopped when the oil pressure increases more than a predetermined value,and the pump is driven when the oil pressure decrease less than apredetermined value. For instance, an applied voltage is decreased whenthe oil pressure increases, and the applied voltage is increased whenthe oil pressure decreases.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features and advantages of the present invention will beappreciated, as well as methods of operation and the function of therelated parts, from a study of the following detailed description, theappended claims, and the drawings, all of which form a part of thisapplication. In the drawings:

[0017]FIG. 1 is a schematic view of an oil supply system according to afirst embodiment of the present invention;

[0018]FIG. 2A through FIG. 2D are oil circuit diagrams showingoperations of the first embodiment, FIG. 2A shows an idle operation,

[0019]FIG. 2B shows a normal running operation, FIG. 2C shows anaccumulating operation and FIG. 2D shows a releasing operation;

[0020]FIG. 3 is a time chart showing an operation of the firstembodiment;

[0021]FIG. 4 is a time chart showing an operation of the firstembodiment;

[0022]FIG. 5 is a time chart showing an operation of the firstembodiment;

[0023]FIG. 6 is a time chart showing an operation of the firstembodiment;

[0024]FIG. 7 is a schematic view of an oil supply system according to asecond embodiment of the present invention;

[0025]FIG. 8 is a schematic view of an oil supply system according to athird embodiment of the present invention; and

[0026]FIG. 9 is a simplified cross sectional view showing a supportedcondition of an electric motor driven pump according to the thirdembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0027] Hereinafter, embodiments of the present invention will bedescribed with reference to drawings.

First Embodiment

[0028]FIG. 1 shows an oil supply system according to a first embodimentof the present invention. The oil supply system 1 constructs a part of acontroller of an automatic transmission in which a transmission ratiocan vary continuously. Such a continuously variable transmission has asecondary pulley 50 and an oil chamber 52 for the secondary. The systemthat supplies oil to the oil chamber 52 is shown in a figure. A pressurein a primary chamber of a primary pulley which is not shown is generatedfrom the pressure in the secondary oil chamber 52.

[0029] The oil supply system 1 has an engine driven pump 10, anelectromagnetic valve 12, an one-way valve 13, an accumulator 20, amotor driven pump 30, a driving circuit 33 and an engine control unit(ECU) 40 as a controller.

[0030] The engine driven pump 10 is driven by an engine output shaftwhich is not shown and is a pump for pressurizing oil. The engine drivenpump 10 sucks oil from an oil tank 11 through an oil passage 100 anddischarges oil into oil passages 101 and 102. The oil passage 101constructs a first supply line. The electromagnetic valve 12 as a firstelectromagnetic valve opens and closes the oil passage 101 in responseto a command signal form the ECU 40. The ECU 40 may be a single unit ora plurality of units. The engine driven pump supplies oil into the oilchamber 52 through the oil passage 101, when the electromagnetic valve12 is opened. The one-way valve prevents that a reverse flow of oil inthe accumulator 20 to the engine driven pump 10.

[0031] The accumulator 20 has a chamber 21. The chamber 21 accumulatesoil discharged by the engine driven pump when the electromagnetic valve12 is closed. The partition plate 22 urged by force of a spring 23pressurizes oil in the chamber at a predetermined pressure. Ifaccumulated oil in the chamber 21 reaches a predetermined amount, apressure regulator valve 24 opens to return excessive oil to the oiltank 11. A sensor 60 as a detecting means detects an amount of oil inthe chamber 21 and transmits a detected signal to the ECU 40.

[0032] The motor driven pump 30 has a main part 31 and a motor 32 fordriving the main part 31. The motor driven pump 30 introduces oil froman oil passage 105 and discharges pressurized oil from the main part 31.A drive circuit 33 supplies driving current to the motor 32 in responseto a command signal transmitted from the ECU 40 to the drive circuit 33.An electromagnetic valve 35 as a second electromagnetic valve isdisposed on an oil passage 103 and opens and closes the oil passage 103in response to a command signal from the ECU 40. The oil-passages 102,103 and 105 construct a third supply line.

[0033] When drive current is supplied from the drive circuit 33 to themotor 32, the main part 31 is driven. When the electromagnetic valve 35is opened, the motor driven pump 30 introduces oil from the chamber 21.When the electromagnetic valve 35 is closed the motor driven pump 30introduces oil from the oil tank 11 through the oil passages 104 and105. The oil passages 104 and 105 construct a second supply line.

[0034] The secondary pulley 50 is a pulley for changing a transmittingratio and for transmitting a driving force to driven wheels. A V-belt 51connects the secondary pulley 50 and a primary pulley which is notshown. The secondary pulley 50 has a groove in which a width is variedaccording to a volume of the oil chamber 52. The primary pulley also hasa groove in which a width can vary according to the volume of theprimary oil chamber. As a result, diameters of the pulleys are changedand a ratio of the revolution speed between the primary pulley and thesecondary pulley is changed. As a result, a control for varying thetransmitting ratio continuously is implemented. An electromagneticregulator valve 55 regulates the oil pressure in the oil chamber 52.

[0035] The ECU 40 inputs detection signals of sensors 60 to 65. Thesensor 60 detects the amount of oil in the chamber 21. The sensor 61detects an oil pressure in the oil chamber 52. The sensor 62 detects arevolution speed of the engine. The sensor 63 detects an oil pressure inthe primary oil chamber. The sensor 64 detects a revolution speed of theprimary pulley. The sensor 65 detects a revolution speed of thesecondary pulley 50. The ECU 40 transmits command signals to theelectromagnetic valves 12 and 35, the drive circuit 33, and theelectromagnetic regulator valve 55.

[0036] Next, an operation of the oil supply system 1 will be describedbased on FIG. 2 through FIG. 6. The description is divided into (1) therevolution speed of the engine and (2) a changing speed of thetransmission ratio. As shown in FIG. 2, arrows indicate a flow of oil.

[0037] (1) The revolution speed of the engine.

[0038] When the engine is in an idle operation, the engine runs under alow revolution state in which the revolution speed is less than apredetermined value. As shown in FIG. 2A, the electromagnetic valve 12is opened and the electromagnetic valve 35 is closed in response to thecommand signals from the ECU 40. The motor driven pump 30 is drivenunder the command from the ECU 40. Therefore, the engine driven pump 10introduces oil from the oil passage 100, the motor driven pump 30introduces oil from the oil passages 104 and 105, and both the pump 10and 30 supply oil to the oil chamber 52.

[0039] The ECU 40 stops the engine, when a vehicle is temporary stoppedsuch as a waiting at a traffic signal and an idle operation in which therevolution speed of the engine is lower than a predetermined value iscontinued not less than a predetermined time. The ECU 40 acts as anidle-stop control means too. The ECU 40 discriminates the stoppage ofthe vehicle by detecting a condition in which the revolution speed islower than a predetermined value and the condition is continued not lessthan a predetermined time. In this case, the ECU 40 automatically stopsthe engine without any operations by the driver.

[0040] After that, if the driver operates an accelerator pedal, the ECU40 detects the operation of the accelerator pedal and resumes a fuelinjection and an ignition. Therefore, the engine is restarted. Duringthe idle-stop operation, oil leaks from the oil chamber 52 and thepressure of oil in the oil chamber 52 is decreased. If the oil pressurein the oil chamber 52 is decreased lower than a holding pressure, thesecondary pulley 50 can't hold the V-belt 51. A primary pressure is alsodecreased, the primary pulley can't hold the V-belt 51 too. In thiscondition, if the engine is restarted, the V-belt 51 slips. And, a shockmight be generated on the continuously variable transmission and thevehicle, because the vehicle is moved when a correct transmission ratiois not obtained between the secondary pulley 50 and the primary pulley.Additionally, the secondary pulley 50 and the primary pulley might bedamaged. To avoid such a problem, the motor driven pump 30 is driven atthe idle-stop operation and supply oil to the oil chamber 52.

[0041]FIG. 3 shows timings (a), (b), and (c) for starting the motordriven pump 30 in the idle-stop operation. In FIG. 3, the motor drivenpump 30 is maintained to be driven until an elapse of a predeterminedtime even the engine is restarted. Because the engine driven pump 10can't supply a sufficient amount of oil to the oil chamber 52 until therevolution speed of the engine exceeds more than a predetermined value.That is similar to FIG. 4, FIG. 5, and FIG. 6. In the case of (a), themotor driven pump 30 is started before the engine is stopped. It ispossible to supply oil into the oil chamber 52 by the motor driven pump30 before the engine driven pump 10 is stopped, by starting the motordriven pump 30 before the engine is stopped. The pressure in the oilchamber 52 is maintained at the holding pressure, even if the motordriven pump 30 has a low performance of supplying oil. A delay time t ispreferable to more than one second. This delay time avoids a driving ofthe motor driven pump 30 when the vehicle moves just after a stop. Inthe case of (b), the motor driven pump 30 is started simultaneously withthe stoppage of the engine. In the case of (c), the motor driven pump 30is started after an elapse of a predetermined time, e.g. after 0.5seconds from the engine is stopped. The pressure in the oil chamber 52is gradually decreased after a temporally increasing by closing thepassage, even the oil chamber 52 is not supplied oil from the enginedriven pump 10 since the engine is stopped. Therefore, it is possible tomaintain the holding pressure in the oil chamber 52, even the motordriven pump 30 is started after an elapse of the predetermined timeafter the engine is stopped.

[0042] Next, a control of an applied voltage to the motor driven pump 30during the idle-stop control will be described with reference to FIG. 4,FIG. 5, and FIG. 6. In FIGS. 4, 5, and 6, the motor driven pump 30 isstarted after an elapse of a predetermined time after the engine isstooped.

[0043] In the case of FIG. 4, a constant voltage is continuouslyapplied. A voltage control is easy. The voltage may be maintained in aconstant value during an ON period, and the constant value may bevaried.

[0044] In the case of FIG. 5, the pressure in the oil chamber 52 isdetected by the sensor 61, and a predetermined voltage is intermittentlyapplied according to the detected pressure in the oil chamber 52. It ispossible to be extended a life span of the motor driven pump 30, becausea total driving time of the motor driven pump 30 can be shortened.

[0045] In the case of FIG. 6, the pressure in the oil chamber 52 isdetected by the sensor 61, a voltage regulated according to the detectedpressure of the oil chamber 52 is continuously applied. It is possibleto be extended a life span of the motor driven pump 30, because anelectricity consumption of the motor driven pump 30 is decreased ratherthan a constant voltage is applied.

[0046] At a normal running condition when the engine revolution speed isnot lower than a predetermined value, as shown in FIG. 2B, theelectromagnetic valve 12 is opened and the electromagnetic valve 35 isclosed in response to the command signal from the ECU 40. The motordriven pump 30 is not driven in response to the command signal from theECU 40. Therefore, the engine driven pump 10 solely supplies oil to theoil chamber 52.

[0047] (2) The changing speed of the transmission ratio.

[0048] As shown in FIG. 2C, at an entire operation range in which thetransmission ratio is not required to change quickly, if the ECU 40discriminates that the amount of oil in the accumulator chamber 21 isless than a predetermined amount based on the detected signal from thesensor 60, the ECU 40 controls the electromagnetic valves 12 and 35 tobe closed with no relation to the operation of the engine. Accordingly,the chamber 21 accumulates oil discharged from the engine driven pump 10through the oil passage 102. When an accumulated amount of oil reaches apredetermined amount, the electromagnetic valve 12 is closed and anaccumulation of oil in the chamber 21 is stopped.

[0049] When a quickly change of the transmission ratio of thecontinuously variable transmission is required, it is needed to supply apredetermined amount of oil into the oil chamber 52 for a short time tochange the groove width of the secondary pulley 50 quickly. It isdifficult to supply the predetermined amount of oil into the oil chamber52 for a short time by the engine driven pump 10 only. Therefore, asshown in FIG. 2D, the electromagnetic valve 12 is closed, theelectromagnetic valve 35 is opened and the motor driven pump 30 isdriven in response to the command signal from the ECU 40. Since theelectromagnetic valve 1 is closed, the engine driven pump 10 doesn'tsupply oil into the oil chamber 52. The motor driven pump 30 introduceshighly pressurized oil previously accumulated in the chamber 21, andsupplies it into the oil chamber 52. Accordingly, it is possible tointroduce a predetermined amount of oil and supply it into the oilchamber 52 in a short time.

[0050] In the first embodiment, the predetermined amount of oil issupplied into the oil chamber 52 in a short time by installing thechamber 21, and introducing oil accumulated in the chamber 21 into themotor driven pump 30. Therefore, it is possible to execute a changingoperation of the transmission ratio quickly. Incidentally, when thecontinuously variable transmission is required a quick change, it ispossible to supply a predetermined amount of oil in a short time eventhe motor driven pump 30 is a small size, because highly pressurized oilin the chamber 21 is supplied into the motor driven pump 30.

Second Embodiment

[0051]FIG. 7 shows a second embodiment of the present invention. Thesame reference numerals are used for pointing components same as thefirst embodiment, and characterizing components of the second embodimentis explained. The start timing of the motor driven pump 30 and thecontrol of voltage applied to the motor driven pump 30 are the same asthat of the first embodiment. In a supply system of the secondembodiment, the engine driven pump 10 and the motor driven pump 30 arearranged in parallel.

Third Embodiment

[0052]FIG. 8 and FIG. 9 show a third embodiment of the presentinvention. The motor driven pump 30 is disposed in the oil tank 11. Thestart timing of the motor driven pump 30 and the control of voltageapplied to the motor driven pump 30 are the same as that of the secondembodiment. A pump such as an impeller type or a scroll type which areoperable in oil and emit low noise is used for the motor driven pump 30.For instance, a volute pump can be used.

[0053] As shown in FIG. 9, the motor driven pump 30 is supported on thesidewall of the oil tank 11 by a stay 71. A vibration proofing rubber 72is disposed between the stay 71 and the oil tank 11. The vibrationproofing rubber 72 suppresses vibration and noise. The vibrationproofing rubber 72 may be disposed between the motor driven pump 30 andthe stay 71. A pressure regulator 45 as a pressure regulating apparatusshown in FIG. 8 is arranged in a discharge side of the motor driven pump30 for regulating a discharge pressure of the motor driven pump 30.

[0054] In this embodiment, since the motor driven pump 30 is disposed inthe oil tank 11, a mounting space for the motor driven pump 30 is notneeded. Therefore, a mounting space for the oil supply system isdecreased. Further, since connections between the controller of thecontinuously variable transmission and the oil passages don't cause aleakage and an introducing of foreign substances, it is not necessary toseal up the connections of the oil passages. Therefore, an assemblingtime of the motor driven pump 30 is shortened.

[0055] Further, since a filter disposed in the oil tank 11 for removinga foreign substances in oil can be commonly used with the engine drivenpump 10, number of parts can be decreased. Further, a pipe forconnecting between the motor driven pump 30 and the controller of thecontinuously variable transmission is shortened. Since a pressure lossof oil supplied from the motor driven pump 30 to the controller of thecontinuously variable transmission is lowered, the system may use amotor driven pump having a low discharging performance. As a result, acompact motor driven pump may be used.

[0056] Further, the discharging pressure of the motor driven pump 30 canbe easily adjusted in a required pressure of the continuously variabletransmission by changing the pressure regulator. A manufacturing cost isdecreased because the motor driven pump can be applied to a several kindof the automatic transmission controller including the controller of thecontinuously variable transmission.

[0057] In the above-described embodiments showing the preferredembodiments of the present invention, the system has the engine drivenpump 10 and additionally has the motor driven pump 30. Therefore, at alow revolution speed, since the motor driven pump 30 can supplement oil,the engine driven pump 10 can be downsized to avoid that the enginedriven pump 10 discharges an excess amount of oil at a high revolutionspeed. As a result, it is possible to supply a sufficient amount of oilto satisfy a demand.

[0058] Further, using a small size engine driven pump 10 decreases loadapplied to the engine and improves fuel efficiency. Further, it ispossible to maintain the oil chamber 52 in the holding pressure by themotor driven pump 30 even the idle-stop control automatically executedis employed. Therefore, when the engine is restarted, since the primarypulley and the secondary pulley can provide an appropriate ratio, thevehicle can start without a generation of shock.

[0059] The present invention can be applied to the other apparatusescontrolled by the pressurized oil such as a automatic transmissionchanging shift ranges in response to an operation of a shift lever.Further, an exact amount of lubricating oil can be supplied by applyingthe present invention to a system supplying oil to a frictional portion.

[0060] Although the present invention has been described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will be apparent to those skilled in the art. Such changesand modifications are to be understood as being included within thescope of the present invention as defined in the appended claims.

What is claimed is:
 1. An oil supplying apparatus comprising: an enginedriven pump driven by an output shaft of an internal combustion engine;a motor driven pump driven electrically and independently of the outputshaft; and a controller for operating said motor driven pump.
 2. An oilsupplying apparatus according to claim 1, wherein: said motor drivenpump is operable in oil.
 3. An oil supplying apparatus according toclaim 2, wherein: said motor driven pump is disposed in an oil tank andsupplies oil to an automatic transmission.
 4. An oil supplying apparatusaccording to claim 3, further comprising a pressure regulator forregulating a pressure of oil discharged from said motor driven pump. 5.An oil supplying apparatus according to claim 1, further comprising afirst supply line for supplying oil discharged by said engine drivenpump and a second supply line for supplying oil discharged by said motordriven pump, wherein said first supply line and said second supply lineare arranged in parallel.
 6. An oil supplying apparatus according toclaim 1, further comprising a first supply line for supplying oildischarged from said engine driven pump, a second supply line forsupplying oil discharged from said motor driven pump, a third supplyline for supplying oil discharged by said engine driven pump to saidmotor driven pump, and an accumulator disposed in said third supply lineto accumulate oil discharged by said engine driven pump and to supplyaccumulated oil to said motor driven pump.
 7. An oil supplying apparatusaccording to claim 6, further comprising a first electromagnetic valvefor closing and opening said first supply line, a second electromagneticvalve for closing and opening an outlet side of said accumulator, andmeans for detecting an amount of oil accumulated in said accumulator andtransmitting a detected signal to said controller, wherein said motordriven pump is arranged to supply oil to an automatic transmission, andwherein said controller closes both of said first and secondelectromagnetic valves when said amount of oil accumulated in saidaccumulator is less than a predetermined amount, and opens said secondelectromagnetic valve and drives said motor driven pump when saidautomatic transmission changes a ratio quickly.
 8. An oil supplyingapparatus according to claim 1, wherein said controller drives saidmotor driven pump when a revolution speed of said internal combustionengine is lower than a predetermined value.
 9. An oil supplyingapparatus according to claim 8, wherein said controller stops saidinternal combustion engine when a condition in which said revolutionspeed of said internal combustion engine is lower than a predeterminedvalue is continued not less than a predetermined time, and drives saidmotor driven pump during said internal combustion engine is stopped. 10.A method for controlling an oil supplying apparatus for supplying oil toan automatic transmission of a vehicle, said oil supplying apparatuscomprising an engine driven pump driven by an output shaft of aninternal combustion engine, a motor driven pump driven electrically andindependently of said output shaft, and an idle-stop controller forstopping said engine in response to a continuous stop of said vehiclefor not less than a limited time, comprising: starting said motor drivenpump simultaneously with said stop of said internal combustion engine bysaid idle-stop controller.
 11. A method for controlling an oil supplyingapparatus for supplying oil to an automatic transmission of a vehicle,said oil supplying apparatus comprising an engine driven pump driven byan output shaft of an internal combustion engine, a motor driven pumpdriven electrically and independently of said output shaft, and anidle-stop controller for stopping said engine in response to acontinuous stop of said vehicle for not less than a limited time,comprising: starting said motor driven pump before said stop of saidinternal combustion engine by said idle-stop controller.
 12. A methodfor controlling an oil supplying apparatus according to claim 11,wherein said motor driven pump is started in response to an elapse ofmore than one second from said stop of said vehicle.
 13. A method forcontrolling an oil supplying apparatus for supplying oil to an automatictransmission of a vehicle, said oil supplying apparatus comprising anengine driven pump driven by an output shaft of an internal combustionengine, a motor driven pump driven electrically and independently ofsaid output shaft, and an idle-stop controller for stopping said enginein response to a continuous stop of said vehicle for not less than alimited time, comprising: starting said motor driven pump after saidstop of said internal combustion engine by said idle-stop controller.14. A method for controlling an oil supplying apparatus according toclaim 13, wherein said motor driven pump is constructed to supply asecondary oil pressure of a continuously variable transmission, andwherein said time from said stop of said internal combustion engine tosaid starting of said motor driven pump is set according to a holdingcharacteristic of said secondary oil pressure after said internalcombustion engine is stopped by said idle-stop controller.
 15. A methodfor controlling an oil supplying apparatus according to claim 14,wherein said continuously variable transmission has a primary pulley anda secondary pulley which are connected by a belt, and wherein said motordriven pump is started in a period of time of which said secondary oilpressure is maintained higher than a pressure that can hold said belt.16. A method for controlling an oil supplying apparatus according toclaim 10, wherein said motor driven pump is continuously driven duringsaid stop of said engine.
 17. A method for controlling an oil supplyingapparatus according to claim 10, wherein said motor driven pump isintermittently driven during said stop of said engine.
 18. A method forcontrolling an oil supplying apparatus according to claim 10, whereinsaid motor driven pump is driven by a constant voltage during said stopof said engine.
 19. A method for controlling an oil supplying apparatusaccording to claim 10, wherein said motor driven pump is driven byvarying a voltage during said stop of said engine.
 20. A method forcontrolling an oil supplying apparatus according to claim 10, whereinsaid motor driven pump is disposed in an oil tank of said automatictransmission.
 21. A method for controlling an oil supplying apparatusaccording to claim 20, further comprising a pressure regulator forregulating a discharged pressure of said motor driven pump.